I have used aviation quality dent filler with success but preparation is extremely important. You need to etch the aluminum chemically then insure it sets up properly before you machine it. Loctite has a professional line of aluminum product which will do the trick. Personal preference is to have the ports welded professionally and no worries.
You could use Muriatic Acid but the fumes would rust everything it comes in contact with like your tools, ferrous metal and parts. Better to use aluminum brightener available from most truck washes or use mag wheel cleaner / Brightener. Always flush with cold water because hot water reacts withe the chemicals and darkens the aluminum.
I have used JB Weld with great results. As doc said, make sure you are clean and that the aluminum is etched. I have had JB in my motor for the last 3 seasons and still looks as good as it did when I put it in.
I have seen some Devcon metal filler at a hardware store, I believe it had a heat rating of 400 F or so. The regular JB weld is like 600 F. I've been looking at auto parts stores and haven't found any Manley or Loctite stuff yet. I kind of hit a speedbump with the cylinder I'm working on right now, had a couple exhaust flange bolts break off in the cylinder. I guess things were just going to smoothly
A forum community dedicated to snowmobile owners and enthusiasts. Come join the discussion about performance, troubleshooting, trails, maintenance, riding tips, modifications, classifieds, accessories, and more!